An exiled Iranian opposition group claims it has evidence of a secret nuclear site under construction in Iran.

A statement released by the Paris-based National Council of Resistance of Iran (NCRI) on July 11 said the site was located in tunnels under a mountain close to the town of Damavand, 70 kilometers northeast of Tehran.

The People's Mujahedin of Iran (MEK), which is part of the NCRI, said the site has existed since 2006 and that Mohsen Fakhrizadeh, a senior official in Iran's Islamic Revolutionary Guards Corps (IRGC), manages a company overseeing the project's "nuclear, biological, and chemical programs."

The MEK, founded in the 1960s to oppose the rule of the Shah, has a mixed track record in exposing alleged nuclear sites on Iran.

It was considered a terrorist organization by the United States until last year.